The verbal disclosure came at a hearing where suspect Aaron Rey Ybarra pleaded not guilty to premeditated first-degree murder and other charges in King County Superior Court.

His defense attorney, Ramona Brandes, has not disputed accounts of the shooting. She maintains Ybarra suffers from mental illness and was unaware of his actions "until he heard a girl screaming."

Under state law, the defense would have to provide written notice within 10 days to reserve the right to pursue an insanity defense.

Ybarra, 26, is accused of fatally shooting a 19-year-old Seattle Pacific University student and wounding two others on June 5. Ybarra was stopped by a student building monitor who pepper-sprayed and tackled him as he reloaded his shotgun, authorities said.

In addition to the shotgun, police say, Ybarra was armed with a hunting knife and carried more than 50 rounds of ammunition.

If convicted of all charges, Ybarra could face a sentence of up to 86 years in prison. King County Prosecutor Dan Satterberg has said. However, a provision of state sentencing law allows prosecutors to seek an exceptional sentence of life in prison "designed for this type of outrageous act of public violence," the prosecutor said.

In addition to the charge of premeditated murder, Ybarra has been charged with three counts of attempted first-degree murder and one count of second-degree assault. All of the charges could carry increased sentences because of firearms allegations.

Prosecutors amended the charges on Monday and added the third count of attempted murder against Ybarra for allegedly pointing a shotgun at a student.

Ybarra is accused of walking into Otto Miller Hall on the SPU campus and shooting three students with a shotgun before he was tackled by student Jon Meis.